Intrauterine growth restriction (IUGR) represents a serious condition that can lead to increased perinatal morbidity, mortality and postnatal impaired neurodevelopment. There are two distinct phenotypes of IUGR: early onset and late onset IUGR with different onset, patterns of evolution and fetal Doppler profile. In early onset preeclampsia the main Doppler modifications are at the level of umbilical artery, with progressive augmentation of the pulsatility index to absent or reverse end diastolic flow. The modifications of the cerebral, cardiac and ductus venosus circulation are generally present, but with different sequences. The late onset IUGR is determined by third trimester placental insufficiency that entails fetal hypoxia. The cerebro-placental ratio (CPR) and the pulsatility index of the middle cerebral artery (PI MCA) seems to be the main markers for both diagnosis and obstetrical management while umbilical Doppler PI is frequently normal. Also the sequence of Doppler alterations is neither specific nor complete. New protocols for the diagnosis and management of late onset IUGR need to be implemented.
Neuroplasticity is a complex process of structural and functional reorganization of brain tissue. In the fetal period, neuroplasticity plays an important role in the emergence and development of white matter tracts. Here, we aimed to study the architecture of normal fetal brains by way of Klingler's dissection. Ten normal brains were collected from in utero deceased fetuses aged between 13 and 35 gestational weeks (GW). During this period, we observed modifications in volume, shape, and sulci configuration. Our findings indicate that the major white matter tracts follow four waves of development. The first wave (13 GW) involves the corpus callosum, the fornix, the anterior commissure, and the uncinate fasciculus. In the second one (14 GW), the superior and inferior longitudinal fasciculi and the cingulum could be identified. The third wave (17 GW) concerns the internal capsule and in the fourth wave (20 GW) all the major tracts, including the inferioroccipital fasciculus, were depicted. Our results suggest an earlier development of the white matter tracts than estimated by DTI tractography studies. Correlating anatomical dissection with tractography data is of great interest for further research in the field of fetal brain mapping.
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